Thermostat.



1. H. BRUHN.

THERMOSTAT.

APPLICATION FILED JUNE 30.1914.

1 206,298. Patented Nov. 28, 1916.

PATENT oFFIoE. 1

JOHN BRUI-IN, 0F SPIRIT LAKE, IOWA.

THERMOSTAT.

Specification of Letters Patent.

Patented Nov. 28, 1916.

Application filed June 30, 1914. Serial No. 848,191.

To all whom it may concern Be it known that I, JOHN H. BRUHN, a citizenof the United States, residing at Spirit Lake, in the county ofDickinson, State of Iowa, have invented certain new and usefulImprovements in Thermostats; and I do hereby declare the following to bea full, clear, and exact description of the invention, such as willenable others skilled in the art to which it appertains to make and usethe same.

This invention relates to thermostats of the type employing a barconsisting of two differentially expansible materials fixed together asa thermostatic element.

More particularly the invention relates to a bar of this descriptionwherein hard rubher is employed as one of the expansible elements.

The principal object of the invention is to provide a novel form ofthermostatic bar for use in connection with a thermostat of thisdescription.

lVith the above and other objects in view the invention consists ingeneral of certain novel details of construction and combination ofparts hereinafter fully described, illustrated in the accompanyingdrawings, and specifically claimed.

In the accompanying drawings, like characters of reference indicate likeparts in the several views, and Figure 1 is a side eleva tion of athermostat having this bar used therein. Fig. 2 is a longitudinalsection through a bar constructed in accordance with this invention.

The thermostat used in connection with this invention is properlyspeaking a twopoint thermostatic switch and comprises a base 10 whereonis mounted a J-shaped metallic frame 11. At the end of the stem of thisframe is an insulator block 12 upon which is supported one end of athermostatic element 13 consisting of a pair of bars having differentlinear coeflicients of expansion under the influence of heat, the barsbeing riveted or otherwise secured together as is common in suchdevices. It is to be noted that this bar consists of two portionsindicated respectively 13 and 13 The portion 13 is of some suitablemetal such as copper or the like and the portion 13 is of hard rubber sothat when the bar is heated it will respond readily to the expansion andassume a curved position as indicated in dotted lines in Fig. 1.

On the base 10 is a binding post 14 adapted for connection of the linewire as will be hereinafter described and through the base and frameextends a contact member 15 which is preferably threaded so that it maybe adjusted to suit varying conditions. This contact member is connectedto the binding post 1 1 by means of a wire 16. On the frame 11 iscarried an insulator block 17 through which passes an adjustable contactmember 18, the frame being provided with an opening of said member ofsufficient size so that the member 18 does not at any time touch theframe 11, the insulating block preferably being provided with a bushingfitting said opening. These parts are so arranged that under normal heatconditions the thermostatic member 13 will have its free end in contactwith the contact member 15 while under conditions of increase of heatthis free end will swing over to the member lS and complete a con tacttherewith. I

It will be observed that the insulation 17 is flush with the outersurface of the bar 11 and that on the member 18 is a lock nut 19. Bymeans of this arrangement the lock nut forms a connection between themembers 18 and 11 when screwed down so that the device, under thesecircumstances becomes a two point thermostatic switch. Ifthe lock nutbescrewed away from the member 11 then there is no circuit betweenmembers 18 and 11 and consequently the device hecomes a single pointthermostatic switch.

Having thus described the invention, what is claimed as new, is

The combination with an insulating base; of a J-shaped conductor platehaving its stem secured fiat on said base, a contact screw carried bythe end of the freearm of the conductor plate and insulated therefrom, asecond contact screw extending through the stem of the plate oppositethe first screw, and a thermostatic expansion member having one endfixed adjacent the end of the stem of the J-shaped member and its otherend located between said screws,

said thermostatic members comprising a In testimony whereof, I afiix mysignastrip of lnsulatlng materlal and a strip of ture, in the presenceof two wltnesses.

conductin material fixed to ether at one T T end, the c nducting stripbein g longer than JOHB BRUHL the insulating strip and having itsremain- Witnesses:

ing end bent around and clamped to the ALBERT E. ALLEN,

remaining end of the conducting strip. V. H. WALBRIDGE.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of I'atents, Washington, D. G.

